NovaGetting a clean photo before you even open the tool
Even lighting matters more than camera quality — a document with one corner in shadow and another washed out by glare is hard to fix afterward, no matter how it's processed. Lay the page flat on a plain, contrasting surface, avoid direct glare from overhead lights, and hold the phone as level and straight-on as possible rather than at an angle, since this tool crops manually rather than auto-correcting perspective.
Cropping out the background
Turning on cropping trims each photo down to just the document, removing the desk, table, or floor visible around its edges. This is a manual crop, not automatic edge detection, so it works best on a photo that was already reasonably straight — cropping can trim the background but can't straighten a document photographed at an angle.
Each photo gets its own crop, independent of the others — move between photos and adjust each one rather than expecting a single crop setting to fit them all, since the framing rarely matches exactly from one photo to the next.
Combining multiple pages into one file
Add one photo per page of the document, in order — reordering and rotating afterward works the same as any multi-image PDF, so it's fine to photograph pages out of order and fix the sequence before creating the final file. Once everything is arranged and cropped the way you want, all the photos combine into a single PDF, the same as scanning multiple pages on a physical scanner.